Expensive pregnancy vitamins that contain fish oils have no effect on the brain development or IQ of children, researchers say.
A new long-term study following children from birth to age seven found mothers who took pregnancy fish oils did not have children with better cognitive, language or development skills than those who did not take them.
It follows a previous study that found pregnancy vitamins in general are a waste of money and that women only need to ensure they are getting the right dose of folic acid and vitamin D.
The new study looked at docosahexaenoic acid (DHA), an omega-3 fatty acid found in fatty fish, such as salmon, and also fish oil supplements.
Pregnancy vitamins containing DHA have become increasingly popular, with Pregnacare Plus costing £15.29 for a month’s supply on Boots.com.
Boots have also brought out their own version costing £12.99. Seven Seas Pregnancy Plus costs £13.69.
The study split more than 600 pregnant women into two groups, with half receiving 800mg of DHA every day for the last half of their pregnancy and the other half receiving a dummy pill.
The results, published in the Journal Of The American Medical Association (Jama), found no differences between the groups when it came to the children’s cognitive, language, and motor development at 18 months of age.
Further tests when the children were aged four showed no benefit of DHA supplements on general intelligence, language, and executive functioning (mental skills that help people get things done).
In fact, researchers noted a possible negative effect on behaviour, as reported by parents, and executive functioning.
Tests on 543 of the children aged seven found the average IQ in the DHA group did not differ from those whose mothers had not taken DHA.
The researchers, led by a team at the South Australian Health and Medical Research Institute, concluded: “This randomised clinical trial provides strong evidence for the lack of benefit of pre-natal DHA supplementation on IQ at seven years and cognition at 18 months and four years, despite higher numbers of pre-term children in the control group.
“Direct assessments consistently demonstrated no significant differences in language, academic abilities, or executive functioning.”
The team added: “The sale of prenatal supplements with DHA continues to increase, despite little evidence of benefit to offspring neurodevelopment.”
Last July, researchers writing in the Drug And Therapeutics Bulletin said pregnancy multivitamins are a waste of money.
A review found “no evidence” that multivitamins result in better health for a mother or her baby and were an “unnecessary expense”.
Instead, experts said women should focus on taking the single vitamins, which are available for a few pence per day, recommended by the NHS.
These are folic acid in the first three months of pregnancy, and vitamin D. They should also follow a healthy diet.